Rapid assessment of endogenous creatinine in physiological samples analyzed by reversed-phase liquid chromatography...

An improved and direct analysis of endogenous creatinine levels using the reversed-phase mode of high performance liquid chromatography (RPLC) is described. The analysis is rapid, the sensitivity of the spectrophotometric detection is in the nanomole range, and the sample preparation requires only filtration to remove the particulate matter. Identification of chromatographic peaks was achieved by means of absorbance ratios, stopped-flow UV spectra and prechromatographic incubation of samples with creatinine amidohydrolase. Reported in this paper are representative chromatograms of samples of amniotic fluid, urine, and cerebrospinal fluid (CSF). The ranges of creatinine concentrations in 10 samples of amniotic fluid, urine and CSF were 0.774--1.850, 99--454.5 and 0.648--1.05 mg/100 ml, respectively. This highly specific and simple assay offers several improvements over previously used methods.